1. Field of the Invention
This invention relates to an improved light beam scanning system.
Light beam scanning systems are comprised of a light beam scanning means constituted of a high-speed motor and a rotating multi-face mirror together with other optical components including, for example, one or more condenser lenses. Such a light beam scanning system is, for example, employed in a light-beam scanning type recording device for scanning a beam of light modulated by the information to be recorded over a recording material.
2. Description of the Prior Art
In conventional light-beam scanning type recording devices, however, it has been necessary for accomplishing high-resolution recording at high speed to rotate a large multi-face mirror at a high rotational velocity. For example, when a 24-faced rotating mirror is used at a duty ratio of 70% to record 4 frames per second, 2,000 lines per frame, 2,600 resolution points per line, it is, when the distance between opposite-facing faces of the rotating mirror is made 120 mm, necessary to rotate the mirror at about 20,000 rpm. When the rotating multi-face mirror is rotated at such a high speed, there inevitably occurs a weight unbalance in the light scanning system due to imprecisions introduced at the time of fabrication of the rotating multi-faced mirror and the motor and at the time of attachment of the multi-faced mirror to the shaft of the motor. The existence of such an unbalance, no matter how slight, will give rise to vibration in the rotating multi-face mirror. The presence of such vibration in the rotating multi-face mirror itself does not, however, necessarily cause jitter in the image since its effect can be eliminated by the use of a linear encoder insofar as the beam incident upon and reflected by the rotating multi-face mirror is a collimated beam at least within the scanning surface. The problem is, however, that the light beam scanning means is mounted on a common optical component mounting plate together with the aforementioned condenser lenses and other optical components so that any vibration in the light beam scanning means is passed on to the other optical elements. As a consequence, these optical components introduce jitter into the light beam which jitter shows up in the image produced.